Debra Newell was a single, successful business owner who had raised her four children when she decided she was ready to go online to try to find love. That’s where she met John Meehan, a man who first seemed like a charming, intelligent doctor but later revealed he was emotionally abusive with a dangerous and criminal past.

TELL DR. PHIL YOUR STORY: Are you involved in a story that has made the headlines?

Newell tells Dr. Phil on Thursday’s episode that as she was trying to end their marriage, Meehan became “psychotic,” set her car on fire, stalked her and eventually showed up to her daughter’s apartment armed with knives.

Newell and Meehan’s story inspired the popular podcast Dear John.

WATCH: Woman Whose Life Inspired Podcast 'Dirty John’ Reveals Frightening Reason She Says She Stayed In Relationship Once It Started To Unravel

In the video above, Dr. Phil explains why he doesn’t believe in giving people the benefit of the doubt. And, he shares with the audience the best way to predict a person’s behavior.

Also on Thursday, Dr. Phil speaks with Andy and his wife, Bridget, who say they were victims of a “virtual kidnapping.”

Watch more in the video above. And, check here to see where you can tune in to Thursday’s show.

TELL DR. PHIL YOUR STORY: Have a story Dr. Phil won't believe?

Red Flags That You’re Being Targeted By A 'Virtual Kidnapper'